Armrest electrical switch array

ABSTRACT

A vehicle interior trim panel electrical switch assembly (10) includes a switch panel portion (16) with a continuous outer surface (18). Force sensitive resistor switches (20a-20g) are supported on the switch panel portion (16) and are secured to the inner surface of a skin cover having a continuous outer surface (18) and forming the outer layer of a soft feel composite. The force sensitive resistor switches are embedded in the soft feel composite either as being cast in a layer of flexible foam or being applied within preformed openings in a layer of flexible foam in certain embodiments in which case they are associated with a circuit module (34) that negates preloading effects due to thermal expansion caused by changes in ambient conditions. In a preferred embodiment the correction occurs due to a circuit configuration that corrects for such preloading effects on a deflection rate basis. The circuit module (34) for each switch (20a-20g) may also include a relay in high power applications.

This nonprovisional application is the National Stage Application ofInternational Application No. PCT/US96/14560, filed Sep. 11, 1996, nowInternational Publication No. WO 97/11473.

TECHNICAL FIELD

This invention relates generally to electrical switches incorporatedinto continuous trim panel surfaces and more particularly to such trimpanels having a flexible outer skin; an intermediate layer of flexiblefoam and a relatively rigid substrate.

BACKGROUND OF THE INVENTION

Soft interior trim panels are currently used for vehicle interiors.These panels generally have an outer cover of leather, a plasticmaterial that is similar to leather or a fabric material. A foammaterial on the back side of the outer cover provides the cover with asofter feel. A substrate is employed on the back side of the foam tosupport the foam and the outer cover and for mounting the soft interiortrim panel in a vehicle. The outer cover or skin, foam backing andsubstrate in combination define a composite that is known as a soft feelcomposite.

Electrical switches are currently used in applications such as armrests, console controls and the other interior trim components that aremade of a soft feel composite. In some cases such electrical switchesextend through an aperture in a bezel that passes through an aperture ina trim panel. Such electrical switches may either be secured to thebezel or attached to the same structure that the trim panel is attachedto. These electrical switches and bezels are hard and rigid. The gapsand cracks formed between the bezels, switches, and a trim panel maycatch on clothing and cleaning materials. The switches have crevicesthat are difficult or impossible to clean out, allow the passage of airand moisture and may transfer heat into or out of a vehicle passengercompartment. Furthermore, noticeable fit and finish problems can arisein such arrangement since it is difficult to always accurately fit abezel around a switch component or switch array. An example of sucharrangements is shown in U.S. Pat. No. 4,975,547.

Membrane switches may also be used in this type of application as isdescribed in U.S. Pat. No. 5,448,028 issued Sep. 5, 1995 to Filion etal. Filion discloses a membrane switch supported by a trim panel beneatha layer of flexible skin. Other examples of multiple sheet membraneswitches for interior applications are shown in U.S. Pat. Nos. 4,612,425and 4,742,192. Such membrane switches are difficult to mold in placewithout introducing preload effects that can cause inadvertent accessoryactuations. Moreover, membrane switches are "on-off" type switches thatdo not allow an occupant to vary the amount of electrical power flowingto the device that the switch controls.

U.S. Pat. No. 5,398,962 has a force-sensitive resistance sensor 30having a low profile that is connected to the underside of a flexibleouter cover and supported against a relatively rigid inner cover thatoverlies an air bag assembly. The sensor 30 is associated with a circuitthat will compensate for thermal differences and includes a circuit thatwill provide a time delay before a given change in resistance will soundthe horn. However, such an arrangement does not define a soft feelcomposite that is suitable for arm rest configurations or for protectionagainst side impacts.

What is needed is an automotive interior door electrical switch arraythat is protected against fluid and dust contamination and is lessdisruptive of interior design contours such as smooth continuous trimpanel surfaces and that will have a soft touch feel and also be able tocompensate for changes in ambient conditions that might otherwiseoperate the switches. To accomplish this objective a conventionalforce-sensitive resistor sensor of the type shown in U.S. Pat. Nos.5,222,399 and 5,086,652 is embedded in a soft feel substrate located ina side impact region of a vehicle wherein the soft feel substrateprotects the switch mechanism. Furthermore, the switch mechanism isassociated with a circuit that will prevent thermal expansion fromadversely affecting the function of the array.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a vehicle interior trim panel electrical switch assembly(10) of the type for actuating various vehicle electrical componentscomprises an interior trim panel (12) including a switch panel portion(16) having a continuous outer surface (18) and an electrical switcharray (20) that is supported on the switch panel portion (16) of theinterior trim panel (12). Characterizing the invention, the electricalswitch array (20) is embedded in a soft feel substrate and the switcharray (20) includes low profile force sensitive resistor sensors (30)that are protected by the soft feel substrate against side impactloading while operating electrical components such as power locks, powerwindow lifts, power seat adjusters and power rear view mirror actuatorsthrough a wide range of ambient temperature conditions.

Unlike prior art door or console switch panels with mechanical switchesor membrane switches the force sensitive resistor sensor (30) of thepresent invention is protected against fluid and dust contamination andcan be molded in place without being disruptive of interior designcontours such as smooth continuous trim panel surfaces while maintainingthe operative characteristics of the switch. Furthermore, forcesensitive resistor sensors have lower profiles than membrane switchesand conventional mechanical switches and therefore take up less space inthe trim panel (12) and can easily be incorporated into or under thecontinuous outer surface (18) of the switch panel portion (16).Furthermore, the embedding thereof in a protective soft feel substratewill protect them against side impact forces.

Incorporating the switch array (20) into a soft feel composite or underthe continuous outer surface (18) enables the switching surface on anarm rest to be substantially flat to define a side arm rest surfaceadjacent vehicle passengers and wherein the side arm rest surface willprovide a comfortable plush feel arm resting surface without impairingthe operation of the switch array. More particularly, the use of forcesensitive resistor sensors (30) provides a surface with continuous softtouch switching features and eliminates the need for a separate add-onbezel in mounting the switches Switches comprising force sensitiveresistor sensors, or "touch" switches as they are commonly called, arealso very light in weight compared to conventional mechanical switches.Therefore, they not only require less space in a trim panel (12), butare also less massive and are less of a factor in vehicle side impactcollisions. Accordingly, they are less susceptable to damage in areassuch as side door arm rest applications and thus can be operatedfollowing such impacts to open windows, adjusts seats or the like inorder to assure easier egress from the vehicle following an accident.

BRIEF DESCRIPTION OF THE DRAWINGS

To better understand and appreciate the invention, refer to thefollowing detailed description in connection with the accompanyingdrawings:

FIG. 1 is a perspective view of a vehicle armrest switch panelconstructed according to the present invention;

FIG. 2 is a cross sectional side view of a portion of the switch panelof FIG. 1 showing one alternative switch sensor installation accordingto the present invention;

FIG. 3 is a cross sectional side view of a switch panel constructedaccording to a second alternative switch sensor installation accordingto the present invention;

FIG. 4A is an enlarged cross sectional view of taken along the line4A--4A in FIG. 1 looking in the direction of the arrows showing raisedareas formed over switch sensors in the continuous outer surface of aswitch panel constructed according to the invention;

FIG. 4B is an enlarged cross sectional view taken along the line 4B--4Bin FIG. 1 looking in the direction of the arrows showing depressed areasformed over switch sensors in the continuous outer surface of a switchpanel constructed according to the present invention;

FIG. 4C is an enlarged cross sectional view taken along the line 4C--4Cin FIG. 1 looking in the direction of the arrows showing raised areasformed around switch sensors in the continuous outer surface of a switchpanel constructed according to the invention; and

FIG. 5 is a cross-sectional side view of a switch panel showing a thirdalternative switch sensor installation according to the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A vehicle interior trim panel electrical switch assembly of the type foractuating various vehicle electrical components is shown at 10 in FIG. 1as an arm rest 12 for a vehicle door 14. The arm rest 12 is formed as asoft feel composite 15, shown in section in FIG. 2, that includes aswitch panel portion 16 that has a continuous outer surface 18 coveringa switch array 20 including eight electrical switches 20a-20h. Four ofthe eight electrical switches are for opening and closing windows, oneof the switches is for locking and unlocking doors, two are forselecting either the left or the right side view mirror for adjustment,and one multiposition switch is for adjusting the position of whicheverside view mirror is selected by the two switches just described.

The arm rest 12 is shown as a separate member from the vertical doorpanel 14, but the arm rest and vertical door panel 14 could be formed asone integral interior panel. Furthermore, the vehicle interior trimpanel electrical switch assembly 10 can be employed on any interiorsurface of a vehicle. It can be part of the dash and instrument panel,part of a headliner and overhead console between seats or any other partof a vehicle interior.

Additionally, the switch array 20 can vary in number and location. Forexample, in another application a single switch can be provided tooperate an overhead light; a power operated sun roof or otherelectrically switched accessory on a motor vehicle. Other arrangementswill depend upon the system being controlled by the switch arrayunderlying a switch panel portion.

The soft feel composite 15 and switch panel portion 16 of the interiortrim panel electrical switch assembly 10 comprises a substrate 22, afoam layer 24 bonded directly to the substrate and a flexible skin 26with an underside surface 28 bonded directly to the foam layer. Theswitch panel portion 16 may be formed from any of a number of well knownmaterials and by any one of a number of methods to include the methodsand materials described in U.S. Pat. Nos. 5,448,028; 5,340,149 and5,280,947, assigned to the assignee of the present invention, andincorporated herein by reference.

A variable resistance sensor 30 is supported on the switch panel portionof the interior trim panel. In accordance with the present invention,the sensor 30 is a force sensitive resistor sensor having a low profilethat allows it to be easily incorporated into or under the continuoussurface of the switch panel portion 16 which adds to the comfort andplush feel of the vehicle interior.

The use of a force sensitive resistor sensor 30 in the embodiment shownin FIG. 2 provides a smooth surface region 32 that has no bumps orridges and thus provides a continuous soft touch switching capability.It eliminates need for a bezel in mounting the switch as shown in priorart arrangements such as shown in U.S. Pat. No. 4,975,547. Also, iteliminates raised surface features such as disclosed in the aforesaid'028 patent. Furthermore, it eliminates the need for multiple sheetmembrane switches for interior applications as shown in U.S. Pat. Nos.4,612,425 and 4,742,192 and can provide a switching function inassociation with an associated circuit or electronic control module 34that can provide an on-off function that is not subject to thermalexpansion differences.

Force sensitive resistor sensors 30 and associated circuit or electroniccontrol modules 34 are light in weight and thin in profile compared toconventional mechanical switches. Therefore, they require less space ina trim panel and are less effected by side impacts when embedded in asoft feel composite. As best seen in FIGS. 2 and 5 each of thelow-profile force sensitive variable electrical resistance sensors (30)(30b) are disposed beneath the continuous outer surface (18) of a switchpanel portion (16). The outer surface (18) has a top surface portion(18a) and a side surface portion (18b). The side surface portion (18b)is located so as to be side impacted by an occupant if there is avehicle crash. As shown, each of said plurality of low-profile forcesensitive variable resistance sensors (30) (30b) are separated from oneanother and from the side surface portion (18b) and are embedded in thefoam layer (24) so as to protect each of the low-profile force sensitivevariable resistance sensors (30) (30b) from side impacts. Furthermore,as shown in FIG. 1, the low-profile force sensitive variable resistancesensors (30) underlying have a side (30s) thereon located in facingrelationship to the side surface portion (18b) and the foam layer 24 inwhich the sensors (30) are embedded will protect the low-profile forcesensitive variable resistance sensors (30) from side impact forces.

The sensor 30, more particularly, is the type of thin profile unit thatwhen flexed has a change of resistance ΔR that, when applied to ancircuit or electronic controller module 34 during a time span ΔT willcause an electronic switch therein to open or close. A drift inresistance due to environment or manufacturing installation does notactivate the circuit. The circuit effectively re-zeroes itself after adrift, since it operates only on ΔR over a time span ΔT as morespecifically set forth in U.S. Pat. No. 5,398,962 which is incorporatedherein by reference.

As described above, the force sensitive resistor sensor 30 is disposedbeneath the continuous outer surface of the switch panel portion and isembedded in the soft feel composite 15 where it is protected againstside impacts and the like. While being protected such embedding subjectsthe sensor 30 to changes in loading due to thermal expansion differencesthat occur during swings in ambient temperature. To avoid the affect ofsuch preloading effects, the force sensitive resistor sensor 30 isassociated with a module 34 that defines a "zeroing" circuit thatnegates preloading effects on a deflection rate basis. Such preloadingeffects are common particularly when a switch is molded in place.Therefore, the zeroing circuit allows the force sensitive resistorswitch to be molded in place, if desired, without adversely affectingcontrol operation. The zeroing circuit also negates long termdimensional changes such as result from thermal expansion. An example ofsuch a zeroing circuit is set forth in the aforesaid U.S. Pat. No.5,398,962.

The module 34 if desired can be directly coupled to a load such that thevariable resistance can increase upon increased finger loading so as toallow occupants to vary the amount of electrical power flowing to theaccessory controlled by the switch by varying the amount of fingerpressure applied to the flexible skin overlying the switch so as toprovide a variable speed window lift action since, if desired anassociated electronic control module can be programmed to produce anoutput that will power an electric drive window lift motor to vary inspeed in accordance with the level of resistance produced upondeflection of the sensor 30. By controlling the amount of electricalpower, occupants can control, for example, the speed of power windowmovement.

In high current applications, a relay 36 may be employed to minimize theamount of current passing through the variable resistor switch as shownin the circuit diagram in FIG. 2 wherein the module 34 is connectedthrough a relay 36 to a load.

The force sensitive resistor sensor 30 is molded in-place between thesubstrate and the skin as shown in FIG. 2. In-place molding may beaccomplished by any one of a number of well-known methods including themethod described in U.S. Pat. No. 5,448,028 and incorporated herein byreference.

The force sensitive sensor 30 may, alternatively, be embedded in theflexible skin. In other words, the switch is held in place asskin-casting material is cast around it as more particularly shown inU.S. Pat. No. 5,269,559 assigned to the assignee of the presentinvention and incorporated herein by reference.

The force sensitive resistor sensor may also be bonded, in apost-applied fashion, to the underside surface of the skin as shown inFIG. 3 at 30a. The underside surface of a flexible skin 26a on a softfeel composite 15a is made accessible via depressions 38 formed throughthe substrate 22a and foam layer 28a. In this embodiment a smoothsurface region 32a can be provided.

In each embodiment shown in FIGS. 1, 2 and 3, many types of adhesives,including acrylics, urethanes, etc., may be used to bond the sensors toa trim panel's outer skin. The adhesives may be applied in any one of anumber of forms to include pressure-sensitive backings and sprayed-onhot melts.

As another alternative, the outer skin can be vac-formed or cast and canbe applied directly over the substrate by vacforming. In the embodimentin FIG. 5, the skin 26b is shown as a PVC layer 26b' with a cast PVCfoam layer 26b". It is directly formed over a force sensitive resistorsensor 30b on a substrate 22b. The force sensitive resistor sensor 30bmay be bonded to the retainer by being vac-formed in place as the skinis vac-formed over the substate 22b. In the embodiment of FIG. 5, thecontrol wires go through pre-existing holes 40 in the substrate 22b andthe sensors 30b are loaded in place. Then the skin 38 is vacuum formedover the entire surface of substrate 22b and mounted sensors 30b. Inthis embodiment the wires are shown connected to a module 34b.

In the various embodiments, the foam material can be molded in place,pre-molded arm can be any suitable foam material that will provide adesired backing, either a soft feel or, if desired, an energy absorbingcharacteristic as provided by the RIM materials disclosed in U.S. Pat.No. 5,232,957 also assigned to the assignee of the present invention andincorporated herein by reference.

Indicia 41 can be printed on an outside face surface of the flexibleskin to indicate to occupants the function of each force sensitiveresistor switch as shown in FIG. 1.

A transparent protective coating 43 may then be applied to the outsidesurface of the flexible skin and to the indicia. The coating is appliedas a liquid and is then dried to form a thin durable protective filmthat keeps the indicia from rubbing off--as is described in greaterdetail in U.S. Pat. No. 5,448,028 and incorporated herein by reference.

If desired, as shown in FIG. 4A at 42, a raised area may be formed inthe flexible skin adjacent the force sensitive resistor sensor forguiding an occupant's finger tip to a location where the occupant mayapply force to actuate the force sensitive resistor sensor.Alternatively, as shown in FIG. 4B at 44, a depressed area may beformed. Other types of surface discontinuities may be formed in theflexible skin as shown by raised nibs 46 in FIG. 4C for the same purposeand may be formed according to methods set forth in U.S. Pat. No.5,448,028 and are incorporated herein by reference.

This is an illustrative description of the invention using words ofdescription rather than of limitation.

Obviously, many modifications and variations of this invention arepossible in light of the above teachings. Within the scope of theclaims, where reference numerals are merely for convenience and are notlimiting, one may practice the invention other than as described.

We claim:
 1. A vehicle interior trim panel electrical switch assembly ofthe type for actuating various vehicle electrical components, saidvehicle interior trim panel electrical switch assembly (10)comprising:an a door arm rest (12) including a switch panel portion (16)having a continuous outer surface (18) including a flat, generallyhorizontally disposed upper surface portion (18a) and a generallyvertically disposed side surface portion (18b); said upper surfaceportion (18a) configured as a side arm rest on a vehicle door and saidside surface portion (18b) located in a position susceptible to sideimpact forces during vehicle crashes; said switch panel portion (16) ofsaid interior trim panel (12) further comprising a substrate (22), afoam layer (24) bonded directly to said substrate (22) and a flexibleskin (26) with an underside surface (28) bonded directly to said foamlayer (24); a plurality of low-profile force sensitive variableresistance resistor sensors (30) disposed beneath said continuous outersurface (18) of said switch panel portion (16) and embedded in said foamlayer (24); each of said plurality of low-profile force sensitivevariable resistance resistor sensors (30) separated from one another andfrom said side surface portion (18b); said foam layer (24) capturingeach of said low profile force sensitive variable resistance resistorsensors; at least one of said low profile force sensitive variableresistance resistor sensors having a side portion (30s) thereon locatedin facing relationship to said side surface portion (18b) and said foamlayer disposed there between for protecting said low profile forcesensitive variable resistance resistor sensors (30) from vehicle crashside impact forces (18b).
 2. A vehicle interior trim panel electricalswitch assembly (10) as defined in claim 1 wherein said low profileforce sensitive variable resistance resistor sensors (30) are attachedto said underside surface (28) of said flexible skin (26).
 3. A vehicleinterior trim panel electrical switch assembly (10) as defined in claim1 wherein said low profile force sensitive variable resistance resistorsensors (30) are attached to said substrate (22).
 4. A vehicle interiortrim panel electrical switch assembly (10) as defined in claim 1 furtherincluding indicia (41) printed on said continuous outer surface (18) indirect overlying relationship to each of said low profile forcesensitive variable resistance resistor sensors.
 5. A vehicle interiortrim panel electrical switch assembly (10) as defined in claim 1 furtherincluding a depressed area (44) in said flexible skin (26) in directoverlying relationship to each of said low profile force sensitivevariable resistance resistor sensors (30).
 6. A vehicle interior trimpanel electrical switch assembly (10) as defined in claim 1 furtherincluding a raised area (42) on said flexible skin (26) in directoverlying relationship to each of said low profile force sensitivevariable resistance resistor sensors (30).
 7. A vehicle interior trimpanel electrical switch assembly (10) as defined in claim 1 including acontrol module (34) having a circuit that is connected to at least oneof said low profile variable resistance resistor sensors and operativeto produce a control output signal in response to a predetermineddifference in resistance following a predetermined time delay followingactuation of the electrical switch assembly.
 8. A vehicle interior trimpanel electrical switch assembly (10) as defined in claim 1 furtherincluding a relay connected to at least one of said low profile forcesensitive variable resistance resistor sensors (30).